It is known for audio signals for hearing aids to be transmitted in analog fashion in the baseband via inductively coupled coils. For example, so-called telephone coils are used to transmit voice signals when telephoning. In addition, induction loops are used in museums, churches, etc. to send signals to hearing aids. As well as this, coils are also used to transmit signals from one hearing aid to another in the case of a cross system (where the hearing aid wearer is wearing two hearing aids).
The analog transmission of audio signals typically takes place using a modulated carrier. To this end, the hearing aids have corresponding AM/FM receivers. In the cross system the behind-the-ear hearing aids also have AM/FM transmitters.
Besides the wireless transmission of signals, wired transmission between the hearing aids is also possible. In addition, wired transmission is possible from an external audio device to a hearing aid via an audio shoe plug.
The article “An Ultra-Wideband Transceiver Architecture for Low Power, Low Rate, Wireless Systems”, IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY, VOL. 54, NO. 5, SEPTEMBER 2005, pages 1623 to 1631 describes a wideband pulse transmission technique for wireless systems. The transmission technique is characterized by low power consumption. The data transmission rate is comparatively high in hearing aid terms.